A wind power generator comprises a generator located inside a nacelle that is supported in a high place by a tower, with the generator being driven by a rotor. A yaw bearing is provided between the nacelle and tower, and supports the nacelle such that the nacelle can rotate in the yaw direction.
Conventionally, when such a yaw bearing became broken for some reason and required replacement, a large crane or the like was used to remove the nacelle and lower the nacelle to the ground, where work to replace the yaw bearing was performed. However, in that case, the cost of the large crane, the cost of labor, the cost of preparing the ground in order to locate the crane and the like, as well as other costs related to the cost of the yaw bearing itself becomes very large.
Moreover, after the tower has been constructed, cancelling the lease of the surrounding ground, restoring the preparations for work to the current state, turning the area into a park, bringing in large, heavy equipment into the area and the like is often not expected, so performing work using a large crane must be avoided as much as possible.
As conventional technology related to maintenance of a wind power generator at high locations of a wind turbine tower, Japanese Laid-open Patent Publication No. 2004-293455 discloses a method of providing a gondola that is raised over a guide rail along the direction of the blades such that workers can ride the gondola and perform maintenance on the blades. Japanese Laid-open Patent Publication No. 2004-512244 discloses a method where in order to perform work such as replacement of component parts in the engine chamber at the top of a wind turbine tower, a service crane for performing work is raised by a permanently installed crane, and work is performed after temporarily securing the service crane to the top of the tower.
Moreover, Japanese Laid-open Patent Publication No. 2009-002175 discloses a method of using a permanently installed winch, which is provided in a girder that moves inside the nacelle, to raise a forward/reverse winch used to exchange equipment that is used for the replacement of wind turbine and a balance that supports equipment for wind turbine, and performing work to replace the winch.
However, by using the conventional technology described above, it is difficult to replace the yaw bearing from the installation position of the bearing, and technology is desired that would allow the replacement of the yaw bearing without the use of a large crane.